Animals possess the flexibility to choose from a variety of behavioral responses in virtually every situation they encounter. Decision-making requires one to gather information from the senses to determine an appropriate behavioral response, taking into account the possible costs or rewards resulting from the alternatives. Risk-prone and maladaptive decision-making characterize a wide range of psychiatric disorders, such as drug addiction and bipolar disorder, but also pertain to such common behaviors as gambling or overextending one's credit. The goal of this proposal is to identify patterns of activity in neural structures involved in evaluating rewards and making decisions between certain and risky outcomes that will inform how risk-preference is represented in the activity of single neurons. Rats will be trained to perform tasks in which they choose between two levers in a test chamber that lead to different reward outcomes (sucrose pellets). In these studies, choices will be based on different reward magnitudes or probabilities of receiving reward. While rats perform these tasks we will record the electrophysiological activity of single neurons in the nucleus accumbens (NAC), which is critical for reward processing, orbitofrontal cortex (OFC), an area thought to be important for making decisions based on reward outcome, and anterior cingulate cortex (ACC), which has been implicated in monitoring conflict and risk. We are interested in how this circuit represents information about absolute reward size (e.g. '3 pellets') to relative value of reward useful for comparison (e.g. 'more than 2'). The long-term goal of our studies is to determine how aberrant signaling in these areas may underlie inaccurate representations of reward which may in turn lead to over-valuation of risky behaviors. PUBLIC HEALTH RELEVANCE: The pervasive problems associated with drug addiction, gambling, or overconsumption (of food or goods) stem from a willingness to engage in behaviors that yield risky outcomes. The goal of this project is to identify how reward expectations- based on the magnitude of the reward and probability of receiving it- are represented in circuitry important for processing rewards and decision-making. These studies have the potential to identify mechanisms underlying risk-preference and therefore new targets for disorders of risky behavior.